The present invention relates to an improved weft ejection nozzle for water jet looms, and more particularly relates to a flow controller of an improved construction and incorporated in the nozzle for inserting a weft into open sheds by entraining same in high speed water jet columns ejected therefrom on water jet looms.
The weaving condition on water jet looms is heavily dependent upon how well the operating fluid can be centripetally directed in order to fully encircle the weft in the water column and how well the operating fluid can be accelerated at the ejection terminal of the jet nozzle in order to entrain the weft with increased propelling force. In this connection, it is well known that smooth centripetal collection and acceleration of the operating fluid flow is seriously hindered by generating of vortical turbulence of the fluid flow during the travel of same from the entrance into the nozzle to the weft ejection terminal of the nozzle. In water jet nozzles of conventional construction, an axially elongated nozzle main body for supply of the weft is housed within a casing while leaving a cylindrical chamber therearound and the operating fluid under pressure is supplied in radial direction into the cylindrical chamber. As a result this forced radially directed supply of the operating fluid should naturally generate a vortical turbulence in the cylindrical chamber which moves towards the weft ejection terminal of the nozzle.
In order to minimize the harmful influence of the turbulence upon the weft insertion, it is required to mitigate the generation of the vortical turbulence of the operating fluid during its travel through the above-described cylindrical chamber.
One proposal has already been made in this sense, in which a thin cylindrical piece having a number of radially aligned through holes is set within the cylindrical chamber while spatially embracing the nozzle main body. With this arrangement, it is intended that the perforated construction of the cylindrical piece should function as a rectifier lattice for the operating fluid.
In practice, however, the operating fluid once introduced into the nozzle under high pressure forms a violent vortical turbulence within the space in the chamber around the cylindrical piece and, due to the small thickness of the piece, the flow of fluid passing through the piece holes cannot be rectified sufficiently. As a result, the fluid flows spouting radially out of the piece holes should again form a vortical turburence within the space of the chamber inwardly of the cylindrical piece. This naturally has a harmful influence upon smooth weft insertion. In addition, the kinetic energy originally possessed by the operating fluid may be considerably reduced through collision with the cylindrical piece, the rectifier lattice, which naturally causes reduced propelling force of the jet water column. So, it is known that the proposal of this type should end in reduced propelling effect with insufficient flow rectifying effect only.
Another proposal has already been made in the above-described sense also, in which a cylindrical piece having a number of axial flow passages is set within the cylindrical chamber of the casing while being snugly inserted over the nozzle main body. With this arrangement, it is intended that the construction with the axial passages should function as a rectifier lattice for the operating fluid.
In practice, however, although this arrangement may assure some flow rectifying effect, it does not serve to centripetally collect the flow of the fluid. Further, in areas of the cylindrical chamber upstream and downstream of the cylindrical piece, some vortical turburences may occur.